Questions tagged [functions]
Questions about the use of built-in Mathematica functions, including pure functions.
2,592
questions
0
votes
1answer
44 views
Using the (long) out of a function to define another function [duplicate]
It might be a trivial question but I haven't been able to find solution myself. Suppose that I have a calculation whose rather long output that is dependent in some variable e.g. ...
1
vote
0answers
63 views
Basic mathematica coding package examples [duplicate]
Since Google and Mathematica documentation has proven utterly useless at answering my question...
Does ANYONE have some BASIC examples of how to code up a package? For my course work, I have to ...
4
votes
0answers
68 views
Using module to define a function that calls another function: Should i use set-delayed (:=) or set (=)
Suppose that I have a function
f[x_,y_,z_]=x*y*z
and now suppose I want to consider a specific application where z is a ...
3
votes
2answers
491 views
How to obtain numerical solutions of a two-variable equation?
I have a two-variable function:
f[x_, y_] := (4 y^2 - 6) (Cos[y π] Cos[x] - Cos[2 y π] Sin[x])
How can I find all the numerical solutions for $x$ and $y$ such ...
2
votes
1answer
70 views
Newton's method of tangents
I am trying to solve this problem.I need to find a zero of a given function with Newton's method of tangents.The condition is
f(x0)*f'(x0)>0
and then calculate ...
2
votes
0answers
20 views
`MatrixFunction` is returning a cryptic error message about “the function `1`”
The "Possible Issues" section of the documentation for MatrixFunction lists several possible ways in which a call to ...
1
vote
0answers
35 views
Need help plotting on Mathematica simple piecewise wave function from quantum physics (Quantum Physics, Griffiths, 2.7) [closed]
On Mathematica need to plot an initial wave function defined as...
Psi(x,0) = Ax when 0 <= x <= a/2
Psi(x,0) = A(a - x) when a/2 <= x <= a
Here is my attempted code...
...
1
vote
1answer
41 views
How to ask the user via Input a Function? - Wolfram Mathematica
I need to ask the user the function to make some procedures. For example, instead of having at the code
f[x_] := Sqrt[1 + x];
and then
...
0
votes
1answer
54 views
Find an instance of a Kaprekar number
Here are two instances of an Kaprekar number
$\text{9${}^{\wedge}
$2 = 81 $\&$ 8+1=9}$
$\text{8${}^{\wedge}
$3 = 512 $\&$ 5+1+2=8}$
There are certainly more with a higher exponent , ...
4
votes
3answers
123 views
Among the first 10,000 multiples of 17
Hello I'm new with Mathematica and I can't find a way where I can do this condition.
Among the first 10,000 multiples of 17 how many have the sum of their digit multiple of 17?
The part for the ...
1
vote
1answer
63 views
Quick & neat Mma actions [closed]
I know that the expressions Series[Exp[x],{x,0,2}] and Exp[x]+O[x]^3are equivalent in Mathematica. I was wondering if a similar ...
5
votes
2answers
85 views
Making functions with the output of a ReplaceAll
I'm trying to make a function from the variable "replace" of next code:
...
1
vote
1answer
29 views
Applying functions to members of members… of lists of lists…, etc
Suppose that I have a list of depth $k$, and I want to apply a function $f$ to all elements at level $n$ - e.g. $f,\{\{\{a,b\},\{b,c\}\},\{\{c,d\}\}\},3\mapsto\{\{\{f(a),f(b)\},\{f(b),f(c)\}\},\{\{f(c)...
1
vote
1answer
55 views
Cache a function in mathematica
I have a function of one variable $f(x): \mathbb{R}\to \mathbb{C}$ which is very difficult to evaluate. Single evaluations may take hours, and I need to use the function at a large variety of points.
...
0
votes
0answers
41 views
Wigner 3j-symbol in mathematica
I am looking for a nice and workable formulation of the 3j-symbol in terms of hypergeometric functions.
On the wolfram webpage I found:
http://functions.wolfram.com/HypergeometricFunctions/...
3
votes
1answer
82 views
What does :Automatic in a function definition mean [closed]
I've been trying to figure it out, to no avail. In reading someone else's code, I come across a function definition, where it says something like this
...
1
vote
1answer
76 views
Is it feasible to curve fit to a staircase function? [closed]
Taking as a starting point the advice given in this post I am trying to fit data to a staircase function as follows:
...
2
votes
1answer
111 views
Plot nested integration of an InterpolatingFunction efficiently
Suppose we have an InterpolatingFunction from NDSolve
...
2
votes
1answer
107 views
For a multivariable polynomial of degree t, how can you find the coefficients of monomials of degree t?
Hello Mathematica StackExchange community,
I'm hoping that someone can be of help!
Let p be a fixed prime. I have a multivariable polynomial g (of degree t). I need a list of all the monomial terms ...
3
votes
1answer
93 views
Mathematica unable to evaluate function which it can write explicitly in simple form
I have a function $\psi(x,n)$ in mathematica which is quite complicated. However, plugging in $n=0$ gives a simple form. Mathematica knows this (see below), however it is still unable to even evaluate ...
2
votes
1answer
34 views
How do I make exponential graph show only one trend-line with two lists of data?
Below is my code containing two lists of data, I need the graph to show one exponential trendline from an exponential equation, but it currently shows one trendline per item in the list. I am sure ...
0
votes
1answer
23 views
Defining a conditional statement for a function
I am trying to define a function that is zero when it is evaluated on real numbers and on a preset list of symbols. I am doing this by using
...
4
votes
1answer
494 views
How this foo, ## & @@ work?
Can anyone explain the code below? The problem is in this part of the code. What is foo, ## & @@? I have been looking at ...
1
vote
1answer
40 views
Little confused about taking transformation
I have a function f, the value of the function at x=0 is zero and at x=2 it is one. I am trying to interchange this, meaning at x=0, f should take the value of one and at x=2 f should be zero. ...
0
votes
0answers
27 views
replacing a founded value in a function
Here is the sample
F[r_] := r^2 + r^3
DerivI[r_] := D[F[r], r]
A = FindRoot[DerivI[r], {r, 9}]
B = F[r] /. r -> A
I want to replace ...
4
votes
2answers
115 views
Making tables and update calculated values
I'm trying to make tables like in the image to calculate max and min of the expressions.
Whenever I change the max and min of a and ...
0
votes
1answer
44 views
Two “different” call of the same expression give two different results… why?
Consider the following code:
...
0
votes
0answers
46 views
1
vote
0answers
63 views
Slot numbers, pure functions [closed]
For the first line of code my function works fine on the list, but when trying to use Map I just keep getting an error (Function::slotn) basically saying there are not enough arguments for it to work, ...
5
votes
4answers
284 views
Recursive function, if and which statements
I am given this question: Let a function $ T_n(x) $ be defined by:
$$
T_{n+1}(x) = \frac{1}{x} T_{n-1}(x) - \frac{2}{7} T_n(x),
$$
where $ T_0(x) = 1, T_1(x) = x $.
I need to construct a recursive ...
1
vote
0answers
28 views
Do I have to write the independent variable always?
I'm not used to using Mathematica. Please help me.
What I want to do is similar to the following:
U and V are unknown function ...
2
votes
3answers
72 views
Function on nested lists
Please can someone help with this question, I'm a bit stuck.
Write a function which will accept a list corresponding to a mark list, where each entry in the mark list has the form ...
5
votes
4answers
220 views
How to Force Evaluation of Derivative in a Pure Function Definition
Let's say I have a function
f1 = #^2 &;
I want to calculate its derivative, perform some manipulations and make the result a pure function. I try
...
0
votes
0answers
24 views
Variant on `PrimeZetaP`
Mathematica has PrimeZetaP for the prime zeta function $\sum_p \frac{1}{p^s}$ where the sum is taken over all primes.
How do I use Mathematica to make an ...
5
votes
1answer
72 views
BreadthFirstScan and DepthFirstScan
Recently, I have been playing with the functions BreadthFirstScan and DepthFirstScan. I'm having a hard time understanding the ...
0
votes
2answers
61 views
Use `If` to create new list from old
I'm trying to use If and AppendTo to create a list by imposing conditions on an initial list. And I'm getting an error that "...
0
votes
0answers
32 views
Pulling answer from previous output
This will probably be a very simple answer. I am trying to find a way to pull the last output from a line and define it as a separate variable so it can be used in a later function. Specifically in ...
0
votes
0answers
47 views
Finding ellipse formulas from set of ellipse relations
Question: Given the ellipse relations below, what additional ellipse formulas/relations/equations can I derive?
I asked a question similar to this in Finding formulas from other formulas and ...
0
votes
2answers
40 views
Truncating digits after calculation
I am working on numerical solutions to PDEs. I get some outputs which I then place back into the original equation to check my answers against expected values which are the original inputs. The ...
3
votes
2answers
83 views
How does mathematica decide what `x_` is in `MemberQ[list,x_/;(x==#)]&/@list`
Consider the following code:
list={1,2}
MemberQ[list, x_ /; (x == #)] & /@ list
This gives {True,True}
...
0
votes
0answers
22 views
Using a Which statement with Graphics3D [duplicate]
*Problem solved in the comments
I am trying to write a function that outputs a different graphic depending on the user's input, with four total options. I was making a test version and am running ...
2
votes
1answer
27 views
StringMatchQ with Alternatives
Why when trying to find whether one (out of several) patterns matches an expression - using StringMatchQ - all of them seem to be ignored and no matches are found?
...
3
votes
3answers
121 views
Is there a way to speed up the following calculation Table[If[TrueQ[],k,Nothing],{k,10^5,10^7}]
I've the following code:
Table[If[TrueQ[2+3^k>2^k+(-1+2^k)*Floor[(3/2)^k]],k,Nothing],{k,10^5,10^7}]
Is there a way to speed the calculation up in Mathematica ...
1
vote
0answers
45 views
Defining function with index [closed]
I have the following relation:
(i=1,...,q).
For defining li, I write:
l[i_] := 2 R Sin[\[Phi][i]/2]
where R is the radius of a circle, l[i] is the i-th length ...
3
votes
1answer
70 views
Plot function with parameters from Reduce
I would like to modify the question a bit. I want to plot the function m with different combination of (a1,b1,a2,b2) over a ...
5
votes
1answer
53 views
Creating a dynamic list of parameter defined functions
I'm trying to create a list of functions that is dynamic in size and defines function names like so:
...
0
votes
0answers
22 views
What is this function syntax doing? [duplicate]
I'm trying to work my way through another person's notebook. I came across this function definition:
...
4
votes
2answers
158 views
How to calculate volume under $ f(x, y) $?
I have the following function:
σ = 0.3;
μ = 5;
cy =0;
cx=0;
f[x_,y_]=Exp[-(1/2)((Sqrt[(x-cx)^2+(y-cy)^2]-μ)/σ)^2]/(σ*Sqrt[2*π])
Plotting this with:
...
1
vote
0answers
52 views
0
votes
1answer
48 views
How to export a table of functions [closed]
Consider a table having rows {a, b, f[a,b,t]}, where a,b are parameters while f is a function of t (being the numeric solution of some differential equation). Is it ...
